First step is to hit f8 when you first turnon computer, then go to (safe mode)
to try and solve your problem is to make the error actually readable. Open your system properties, click the advanced tab and then the settings button under startup and recovery. Uncheck 'Automatically Restart' and OK all of the open windows. Next time a stop error is generated you should be able to see it now. (Write the error code down and the someone can debugged it errors will look like 0x000000007 for exsample.)
Stop errors can be caused by a variety of things such as faulty hardware, bad device drivers, overclocking/over heating issues or software trying to do things it shouldn't or is not allowed to under Windows XP.

hi again, thanks for your advice, i just rang my friend and talked her through what you said but nothing happened, just the error flashing up then gone again.

Couldn't get into safe mode reformat drive is the only solution. If it doesn't go thought setup window xp correctly or wiht a lot of error you might have bad Ram.

your brill but talking to a pc dim wit, how do we reformat please?

i really am a dim wit when it comes to fixing problems. thanks for all your help though.

If it a compaq or HP Computer ou have to hold the F10 button when you turn on the computer and it start system recover if it not a retail computer but custom built you need you windows XP disk and have to load it when you are turning on your computer and hve the computer boot from cd.

This might help:

Press del key when booting to get to the bios settings menu (if that doesn't work try f2 or f10)

Select somthing that sounds like "LOAD DEFAULT BIOS SETTINGS" or "LOAD DEFAULT SYSTEM SETTINGS". Later one is advised.
Save the changes.

Plaese post any further questions.